Does the prayer of a wife, praying behind her husband who has a lisp, become invalid, and is the husband sinful for leading her in prayer, and does the ruling differ between silent and audible prayers?

The wife's prayer behind her husband who lisps, replacing one letter with another, is not valid unless the wife also lisps. This ruling applies to both audible (jahrī) and inaudible (sirrī) prayers. The husband does not incur sin by leading his wife in prayer, but he must inform her that her prayer behind him is invalid if he is aware of it.